Sunlight, cancer, leukemia & cancer prevention

extracted from Dr. Damien Downing's book "Daylight Robbery — The Importance of Sunlight to Health" (Chapter 6: The Big C & a Little UV)

Sunlight is a killer! This is the clear message from the medical profession at present. The warm, sensual feeling that you get from lying in the sun is probably immoral, and you ought to be at home taking antibiotics. Yet we persist in taking holidays in the sun, and nipping out of doors at lunchtime. Can it be that we know something the doctors don't?

It definitely can, and some of the evidence to prove us right has been around for half a century. Put aside for a moment the question of skin cancer — which is dealt with in the next chapter [Skin Cancer, Malignant Melanoma and Sunlight] — and think about cancers in general, which kill far more people every year.

Twenty-five years ago Dr John Ott investigated the background to a report that children at a school in Illinois had five times the national rate of leukaemia.[1] He found that the schoolhouse was a plain, modern building with very large windows in every room, and all the pupils who developed leukemia had been in two particular classrooms. In these two rooms the teachers always kept the large curtains completely drawn across the windows to reduce glare and distraction, and to keep the children's attention on schoolwork.

The indoor lighting was therefore on all the time, and this was 'warm white' fluorescent. The whole class spent its working day in light of twilight intensity, with no blue or UV light at all except at playtime — and in Illinois they have some hard winters, during which the children might not go out to play at all.

Several years later the two teachers in question left the school, and their replacements kept the classroom curtains open all the time. The lights were also replaced with cool white fluorescent ones, and of course needed to be used less. From then on there was not a single case of leukemia in the school for as long as Dr Ott followed it up. No other explanation has been put forward for this remarkable mini-epidemic of leukaemia; although in isolation it proves nothing, it started Dr Ott thinking about the possibility of a link between sunlight and cancer.

In fact this had been commented on half a century ago. In 1936, a report in The Lancet by Peller, a US Navy doctor, suggested an inverse relationship between skin cancer and all other cancers. He observed that Navy personnel had eight times the skin cancer rate of the rest of the population, but only forty per cent of the total death rate from cancer.[2] He proposed that the obvious explanation for this was the greater amount of sunlight to which men serving in the Navy were exposed. Nowadays, many naval personnel probably spend their whole working lives at computer consoles, but in 1936 they naturally led an outdoor life and were in the sun a great deal.

Peller made the startling suggestion that by using high intensities of light, either sunlight or ultraviolet from a carbon arc lamp, we should actively induce skin cancers in patients, in order to protect them from other cancers.

As cancers go, those skin cancers that have been clearly shown to be related to sunlight have obvious advantages; the most important of these is that they are visible at a much earlier stage, and can therefore be dealt with. The success rate of surgery has always been good, and if you had to choose which cancer to get, skin cancer would be an excellent choice.

In fact, skin cancers cause only nine per cent of the deaths from cancer every year, and organ or internal cancers ninety one per cent. What's more, the survival rate from skin cancer is very good — about ninety five per cent of sufferers live for five years or more after diagnosis, whereas only thirty six per cent of cancer victims in general live that long. The exception, of course, is the relatively rare skin cancer called malignant melanoma, which is discussed in the next chapter.

The global view

The really strong sunlight effect starts to show through when you examine the relationship betweeen sunlight exposure and cancer incidence on a global scale — the epidemiology. This has been looked at in some detail on several occasions.

The simplest and clearest study is that performed by Hoffman for the Prudential Life Assurance Company in 1924.[3] He analysed the frequency of cancers of all types in a total of 130 cities around the world (looking at almost 300,000 cancer deaths) and matched this against their latitude. The results are clearly shown in the graph above. The further the city from the equator, the greater the number of cancers. The ratio of highest frequency to lowest is around 2.5:1, which looks as though it may turn out to be a magic figure of some sort.

This study concentrated on people living in cities, so that factors such as lifestyle and levels of development shouId not interfere. But in 1940, when Dr Frank Apperley looked at the total mortality from cancers across the United States in both rural and urban areas, the picture he found was just the same, and very clear. He measured two factors that are likely to match closely with the average exposure of individuals to sunlight: the percentage of the population involved in agriculture (and so out of doors most of the time), and the amount of solar radiation recorded by the local Met station. He plotted these measures against the number of cancers.

This was then refined further by looking only at people over forty five (the age group in which the large majority of cancers occur), and only at the white population, who have an incidence of cancer several times higher than that of black people. Neither of these restrictions altered the results at all; the effect was the same for both methods of analysis. As you can see from the graph, the more time people are outdoors, and the more sunlight in the area where they live, the fewer cancers they develop. Interestingly, the highest ratio comes out once again to a little over 2:1.

So what mechanisms could explain this link between light deficiency and cancer? Well, several of them. The problem with researching this kind of thing is that there is no single clearcut process involved to make it nice and easy for the scientist. Sunlight is so fundamental to our lives, and affects us in so many ways, that it may be impossible to demonstrate a single link. But we can pull several strands out of the knot, each of them a connection.

The guts of the matter

In a large North American study, higher vitamin D levels appeared to give significant protection against cancer of the colon. The analysis made was of the amount of vitamin D in the diet, not of blood levels. The researchers found that the group with the lowest vitamin D intake were about 2.5 times more likely (there's that number again) to develop bowel cancer than those with the most vitamin D in their diet.[4]

We know that much of the population in this country [presumably Great Britain] is vitamin D-deficient for much of the year, even more so than in America. Raising people's levels of this vitamin may protect them in some way from cancer.

However, when this connection was examined in Japan, there did not appear to be the same correlation. This may be due, suggests the paper, to the fact that the Japanese, living nearer the equator, have a greater exposure to sunlight, and therefore more sunlight-derived vitamin D in their blood.[5] In these circumstances, dietary vitamin D will not be so important.

The best-known reason why vitamin D is important is that it increases our uptake of calcium from the diet. We know that calcium plays an important part in cancer of the bowel, actively calming down the rapidly dividing cells. Vitamin D will enable these cells to take up more calcium, and this may begin to explain the sunlight effect. More recently, laboratory studies have found that there are receptor sites for vitamin D on cancer cells, and that it appears capable of converting human leukaemia cells back into normal cells — at least in the test tube.

A breach of security

It has been estimated that we each develop cancer once a week on average. This is how often a cell in our bodies is likely to go "rogue" and start dividing rampantly. But fortunately for us, when this happens the cell also undergoes a change in the proteins on its surface, and our immune system swiftly identifies it as "not-self", as a threat to our health, and eliminates it. In other words, developing a cancer — a real cancer — is a sign not of something going wrong with our genes, but of something wrong with our immune systems.

This is why people with AIDS are so vulnerable to strange malignancies such as Kaposi's Sarcoma. Their immune systems are damaged by the virus, which attacks the T-cells, a type of white cell crucial to the production of antibodies against invaders. AIDS particularly kills off the T-helper cells, which are normally in balance with T-suppressor cells. T-helpers stimulate the immune system to attack, while T-suppressors discourage it from so doing. With a disproportionately low level of T-helpers the immune system is powerless against infections, cancers and other threats to our wellbeing.

Yet there are people alive in America who have had AIDS for several years but are now fit and well. They have found ways to stimulate their bodies' production of T-cells when conventional drugs were powerless to help. A variety of methods appear to have benefited them — meditation, herbs, acupuncture and megadose vitamin C among the most important.

It is now clear, from very recent studies on the skin as an immune organ, and from old studies on the effects of sunlight on the white blood cell count, that sunlight can have a dramatic effect in this area. When sunlight hits the skin, it stimulates the topmost layer of living cells, the keratinocytes. These are the cells which produce the keratin, the hard outer layer of dead skin that protects us from germs and injuries.

It was always thought that they had no other function. But new evidence has proved that when they are triggered by ultraviolet light, keratinocytes produce a chemical called interleukin-1. IL-1 has a simple but potent effect: it causes white cells, and T-cells in particular, to multiply in number.

Since this is the only way that such cells can be mobilised quickly to respond to a threat, IL-1 has been the focus of considerable interest among immunologists in recent years. Despite detailed research, though, it has been clear that we are a long way from the day when we can synthesise it in a laboratory. Now there hardly seems to be any point. Why spend millions on manufacturing something which our own bodies will make for free in response to sunlight?

So in order to raise your white cell count, mobilise your immune system against attacks by infection or even by cancer, and absorb more protective calcium, all you need to do is sunbathe. This may help to explain why children get so many infections in winter, when we are all at risk from sunlight deficiency — and why influenza epidemics alway seem to happen then too. But it may also be an important strand in the understanding of why sunlight protects against cancer.

Free oxidising radicals

Free oxidising radicals are small negative ions with the ability to split molecules and damage cells. These atoms and small molecules with a negative charge on them are produced in chemical reactions, in the atmosphere, in food and in our bodies. Some of them are very short-lived, only existing for minute fractions of a second. However, they have a tendency to propagate rapidly, so that the production of one free oxidising radical (FOR) can, within a very short space of time, lead to a large number.

Whether single or multiple, they have a powerful ability to react with biological molecules in damaging ways. They can break open the DNA in our chromosomes, although there are mechanisms to prevent their getting near it in its safe harbour in the cell nucleus. When they do come into contact with DNA they can split it open and alter the genetic information, leading to mutations.

They also split open antibodies, the molecules used by our immune systems to attack infections and clear allergens out of the system. This can lead to effects very like allergic reactions in some people. Also, they can break open collagen molecules, the structures that make up ligaments and hold our tissues together, and give skin its elasticity. This is why pollution and smoking can age your skin.

On the other hand, free oxidising radicals are actually used by the white cells of the body to attack infecting agents. As a white cell engulfs a virus or bacterium, it pumps highly toxic FORs into the forming vacuole in order to kill the micro-organism. Thus FORs are necessary to the healthy functioning of our immune system; in other words, they are an example of something that is necessary in the right amounts, but can be toxic in overdose.

Our bodies possess a series of mechanisms for controlling FORs, mopping them up rapidly and preventing them from damaging tissues. These are known as antioxidants. The major ones are essential nutrients such as vitamins A, E, and C, the amino-acid glutathione, and certain minerals such as selenium.

Some of these, such as vitamins A and E, protect by mopping up FORs themselves, so preventing them from damaging our cells. Others, such as selenium, are components of the enzymes which rapidly process and inactivate FORS. Damage produced by smoking, alcohol, radiation or even sunburn due to ultra-violet light, are all FOR effects. They are all prevented by high levels of antioxidants, in this case particularly vitamin A.

So FORs can be produced by large doses of ultraviolet light, but we can protect against this by an adequate intake of antioxidant nutrients, and by avoiding excess fat in our diet. Since we live in a light-poor environment, diet is more important in this respect than overdoses of light, with the exception of the annual jaunt to the Costa Packet.

Torremolinos in summer is full of English people overdosing on sunlight, on alcohol, on greasy food, possibly on tobacco too. Along with the raffia ponies and peeling backs, they bring home a system so overloaded so rapidly that they may need the rest of the year in a dark room to recover. That we do not all develop skin cancer after our summer holidays only proves the effectiveness of the body's defences when we are in good health.

Fat and weak

Some of the molecules most vulnerable to the effects of free oxidising radicals are the oils and fats making up our cell walls, which are obtained from our diet. It is now well understood that the more oils there are in our diet the more antioxidants we need to protect them. Without these protective mechanisms, the fats may be damaged by FORs, and it is thought that their molecules may be twisted into an abnormal and highly toxic form, known as trans-fats.

The greater the surplus of fats and oils over antioxidant nutrients in our bodies, the greater the probability of trans-fats being formed, and this alone may explain many cancers. Overdoses of ultraviolet light may cause this change, but only if we are short of the protective nutrients. Once again it is a matter of nutritional balance.

Despite the current powerful trend of opinion against them, it appears that saturated fats are not in themselves toxic. They do harm us, though, in two specific ways. Firstly, a high animal-fat diet may contain simply too much fat surplus, with the risk of trans-fats being formed. But polyunsaturated oils too can cause both of these damaging effects, so lashings of sunflower oil or margarine on your baked potato may be just as harmful as butter.

Secondly, saturated fats, which have no double bonds along their chain of carbon atoms, can simply replace unsaturated fats in the diet, and some unsaturated oils are necessary for health. The importance of unsaturation is that it means the presence of double bonds in the chemical structure of the oil. These double bonds can be opened up by enzymes and used, rather like a child's construction toy, to build new molecules.

This enables the oils to be utilised by the body for cell walls and for the production of a range of other chemicals; in particular for a group of hormones called Prostaglandins. Because we need a regular supply of them to process into other molecules, certain of these oils and fats are known as essential fatty acids.

Prostaglandins control a large variety of biological functions, including inflammation in response to injury or infection, the formation of blood clots in arteries and veins, and the contraction of the uterus in childbirth. Saturated fats are useless in this respect, and are therefore only able to be stored and used as calories. We need polyunsaturates for normal functioning, but the greater our intake, the more molecules we have circulating which need to be protected against FOR damage, including that from UV light.

Human studies

In 19S9 Dr Ott finally had the opportunity he longed for: he was asked to participate in a study on the effects of sunlight on cancer in human patients. A physician at the Bellevue Medical Center in New York arranged for fifteen people with diagnosed cancer to organise their own sunlight therapy.

Throughout the summer months, they spent as much time as possible out of doors, without any glasses or sunglasses. They also avoided artificial lights and televisions as much as possible.

When the summer ended, the physician in charge attempted to evaluate the results. She found that fourteen out of the fifteen patients had shown no further spread in their cancers, and some even appeared to have improved. The fifteenth had continued wearing spectacles, and so would have blocked ultraviolet light from entering her eyes.

Although there were no controls in this experiment, and it had run for only a few months, both Dr Ott and the doctor thought that it showed sufficient effect to be worthy of further, more detailed, investigation.

The medical authorities to whom he presented these results, with a proposal for further research, thought otherwise, and no more research was done on humans. But another medical friend of Dr Ott's did become interested, and set up an experiment using a strain of mice (known as C3H mice) that are very prone to developing cancerous tumours spontaneously. He reared separate litters under pink fluorescent tubes, under 'daylight' white tubes and under sunlight, The mice under the pink tubes showed cancers first, a month before those under white tubes and three months before those in daylight.

Strangely, this study was refused for publication! Much more work will have to be done before the medical community will accept any value for light in treating cancer, and there is no sign of it being done at present. Yet the results of the small study on humans were strongly positive, and any drug company would be delighted if it would show such a positive response to their product after only a few weeks.

Take all of this evidence together and a pattern does emerge. It seems clear that we can modify our lifestyle in one simple way that will decrease our risk of developing cancer, and may even offer hope of help when we do develop it.

1. Ott, John, Health and Light, Pocket Books, New York, 1973.
2. Peller, S., 'Skin Irradiation and Cancer in the U.S. Navy', American Journal of Medical Science: 194; 326-333, 1937.
3. Hoffman, F.L., The Mortality of Cancer Throughout the World, Appendix E, Prudential Press, 1915.
4. Apperly, F.L., 'The Relation of Solar Radiation to Cancer Mortality in North America', Cancer Research.
5. Garland, C., et al., 'Dietary Vitamin D and Calcium and Risk of Colorectal Cancer', Lancet: 1; 307-309, 1985.

About the author of Daylight Robbery — The Importance of Sunlight to Health

Dr. Damien Downing M.B., B.S., Lic.Ac.Dr Damien Downing M.B., B.S., Lic.Ac.
Qualified at Guy's Hospital, London in 1972, and worked in hospitals and general practice in London, Leeds and York. He spent three years in the Solomon Islands as Medical Officer of Health for the capital, with responsibility for Mental Health Services and the Village Aid Project. On his return to the UK in 1980 he established a private practice, focusing on nutritional and alternative therapies.

Since 1980 his work has established him as a leading figure in nutritional medicine in the UK. He has undertaken pioneering work in the treatment of allergy, the linking of behavoural disorders with nutrition, light therapy and the treatment of M.E./C.F.S.

In 1984 he co-founded the British Society of Nutritional Medicine with three colleagues and he is still on the committee of its successor, the BSAENM. Since 1989 he has been first co-editor, now senior editor, of the Journal of Nutritional and Environmental Medicine.

In 1991, with Professor R Lacey at the University of Leeds, he co-founded Parascope, a joint-project laboratory investigating intestinal parasitosis. He is a medical advisor to the Hyperactive Children's Support Group and to several other charities.

He currently lives in London. (Bio courtesy Nutrition Associates)

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